1. Field of the Invention
The present invention relates to a pneumatic tire provided with a rim protector, and in more detail, the present invention relates to a pneumatic tire with protection performance of a rim secured and with durability at bead portions improved.
2. Description of the Prior Art
In a pneumatic tire with low flatness ratio, tire sectional height is low and the height to a rim of a wheel from a road surface also becomes low. Therefore, not only a sidewall portion of a tire, but also a rim gets contact with a curbstone when a tire gets contact with a curbstone, and the rim gets some damages such as scar, deformation, and the like, which sometimes causes air leakage.
In order to prevent such damages of a rim, circular protrusions (rim protectors) continuous in a tire circumferential direction and protruded outwardly in the tire width direction are provided on a portion near beads of a side wall. Even when a tire approaches a curbstone, first, said rim protector gets contact with a curbstone, and therefore, a rim is protected and damages of the rim can be prevented. For example, a pneumatic tire provided with rim protectors is publicly known in FIGS. 1 and 2, pages 1 to 2 of Japanese Patent Laid-Open Publication No. 2002-59712.
In such a conventional pneumatic tire, when the tire strongly gets contact with a curbstone, rim protectors are largely deformed subject to strong impact from the curbstone. Then the rim gets contact with the curbstone and gets damaged. In addition, satisfactory protection for rims has been made raising the protrusion height of protectors so that various kinds of flange-like rims can be protected. However, when the protrusion height of protectors is raised, since the volume of the rim protectors gets large, heating at bead portions gets large, too. As a result, a problem of degraded duration performance at bead portions has also occurred.
In the pneumatic tire of the Japanese Patent Laid-Open Publication No. 2002-59712, such a structure was made that concave portions are arranged on rim protectors with intervals, and concave portions and convex portions are alternately arranged. As a result, weight saving of protectors is attempted by decreasing the volume of the protectors due to the concave portions, however, the effect of weight saving has not been satisfactory. In addition, by providing the concave portions, although a surface area increases, heat is likely to be entrapped in the concave portions and radiation effect has not been satisfactory, either. As a result, the effect of improving durability of bead portions has been little.
Therefore, the object of the present invention is to secure the protection performance of a rim and improve the durability of bead portions.